Communication systems and networks are designed and dimensioned by operators to handle a particular average traffic situation. This means that the networks are dimensioned for a certain amount of traffic and configured to support a given mixture of application flows. In the communication networks of today, a vast range of different such applications flows can be present, where each flow has specific characteristics in terms of requirements on transport quality of service (QoS), but also in data packet size, length of data flow in time, traffic intensity spread over the day, etc. This information is utilized by the network operator to compile a traffic model, based on which the network is dimensioned and built.
This means that a particular communication network is designed for (effectively) handling a particular traffic model that typically represents the average expected traffic pattern in terms of the number and types of connected communication terminals and the number and types of data flows.
However, in wired and in particular wireless communication networks, the traffic pattern can dynamically and locally change over time implying that the actual traffic situation in a portion of the network can, at least temporarily, significantly diverge from the average expected traffic situation represented by the traffic model. As the communication network is not designed to effectively handle such a diverged traffic situation, the users will typically experience a reduced quality of service in terms of disconnected calls, prevention of access to the communication network, prevention of using certain applications/services and operation of applications/services at a low QoS.
Design of an appropriate traffic model becomes even more challenging for the network operators today with the increase in the number of available application and service data flows and different user terminal types that can be present in the network. For example, traditionally a regular voice or conversational service was a single uniform communication service in wireless radio-based systems. However, today the network operators and service providers can offer different QoS levels and usages for such voice services. A user having a “gold” subscription with the operator could be prioritized higher than a “regular” user. This means that even though similar data flows originate from the gold and regular user, the network should handle these flows differently by giving priority to the former, possible at expanse of the latter.
Also the new IP-based services, such as Web browsing, multimedia services, etc. emerging in different wireless communication networks render it more difficult to optimally design and manage communication networks.
The traditional approaches of coping with a divergence from the pre-defined traffic model in terms of a change in user behavior, number of connected users, type of connected users and distribution of application data flows to provide adequate QoS, at least to the prioritized users, include utilizing an admission control procedure. This means that a decision whether to accept or reject a new connection is made depending on the interference or load it adds to the existing connections. Such an admission control could also be made dependent on different QoS classes of the users, see the document [1].
This admission control can also be complemented with congestion control that is put into action when the admitted users cannot be satisfied with the normal agreed QoS due to an overload. In this congestion control, an update of the transmission scheduling schemes is typically employed as in the document [1]. This means that the time occasions allocated to particular users for data transmissions are reduced.